Approach control for grinding machines



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- f' @uwlLL/m OQ-r-ronmevf United States Patent O 3,494,079 APPROACHCONTROL FOR GRINDING MACHINES Arthur Klein, Netphen, Germany, assignerto H. A. Waldrich G.m.b.H., Siegen, Westphalia, Germany Filed July 10,1967, Ser. No. 654,032 Int. Cl. B24b 49/02 U.S. Cl. 51--165 7 ClaimsABSTRACT OF THE DISCLOSURE For automatically reducing the rate ofadvance of a grinding wheel toward a work roll when the periphery of thewheel is a predetermined distance short of the roll, a roll feelerprojecting in front of the wheel periphery engages the roll ahead of thewheel to detect the diameter and location of the roll, shifts rearwardlyrelative to the wheel as a result of such engagement, and acts through afloating differential lever to shift a wheel feeler forwardly intofeeling engagement with the wheel. In moving into feeling engagement,the wheel feeler senses the prevailing diameter of the wheel and reducesthe rate of advance of the wheel when the latter reaches a positiondetermined both by the diameter of the wheel and the diameter of theroll.

BACKGROUND OF THE INVENTION This invention relates to a grinding machineof the type in which a carriage supporting a rotatable grinding wheel isadvanced at a rapid rate toward a work roll to bring the wheel intooperative position for effecting grinding of the roll as the advance ofthe carriage is continued at a slow feed rate.

SUMMARY OF THE INVENTION The present invention insures that, in spite ofwearing down of the grinding wheel to a reduced diameter and regardlessof the diameter of the roll to be ground, the rate of advance of thewheel always will be reduced when the periphery of the wheel is a fixeddistance short of the roll. For this purpose, a roll feeler projectingahead of the periphery of the wheel engages and detects the diameter ofthe roll upon rapid advance of the carriage and acts through a floatingdifferential lever mounted on the carriage to project a wheel feelerinto feeling engagement with the wheel. The latter feeler, when infeeling engagement, detects the prevailing diameter of the wheel anddelays the changeover in the advance rate until the distance between thewheel and the roll is correlated not only with the diameter of the rollbut also with the diameter of the wheel. As a result, a wheel of anydiameter may be rapidly approached to just short of a roll of anydiameter and yet with no danger of the wheel hitting the roll whilebeing rapidly advanced.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a fragmentary plan view ofa grinding machine embodying the novel features of the presentinvention.

FIGS. 2 and 3 are enlarged fragmentary cross-sections taken along thelines 2-2 and 3-3 of FIG. 1.

FIG. 4 is an enlarged cross-section taken along the line 4-4 of FIG. 3and showing parts in moved positions.

FIG. 5 is an enlarged fragmentary cross-section taken along the line 5-5of FIG. 3.

FIG. 6 is an enlargement of part of FIG. 3 and showing the parts inmoved positions.

FIGS. 7 to 12 are fragmentary views similar to FIG. 2 and schematicallyillustrating the parts on an exaggerated scale and in various movedpositions.

FIG. 13 is a fragmentary circuit diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENT For purposes of illustration,the invention is shown in the drawings incorporated in a grindingmachine of the type commonly used to rough and finish grind the surfaceof a generally cylindrical mill roll 20 (FIG. l) while the latter isrotated about its longitudinal axis on steadyrests 21 upstanding from asupporting bed 23 by a motor (not shown) driving a headstock 24 chuckedto one end of the roll. Grinding of the roll is effected by a rotatableabrasive wheel 25 mounted on a carriage 26 for `movement in arectilinear path toward and away from the roll as the carriage is slidback and forth along ways 27 on a sub-carriage 29 which, in turn, slidesalong a second set of ways 30 on the bed 23 to move the wheel along theface of the roll in response to turning of a lead screw 31 connected tothe sub-carriage and rotated by a drive motor (not shown). The grindingwheel is fast on and rotated by a horizontal spindle 33 journaled in thecarriage 26 and connected by drive belts 34 to an electric motor 35which is supported on a platform 35a on one side of the carriage.

With an unfinished roll 20 in place on the steadyrests 21, a poweroperator 36 (FIG. 7) advances the grinding wheel 25 toward the roll intwo-step cycle including rst advancing the wheel rapidly from aretracted position (FIG. 7) to a position shown in FIG. l0 in which theperiphery of the wheel is just short of the roll and then continuing toadvance the wheel at a slower feed rate into contact with the roll toeffect grinding thereof. Herein, the power operator comprises areversible rapid traverse motor 37 (FIG. 7) mounted on the carriage 26and connected by reduction gearing 40 to a nut 41 journaled in a bearing(not shown) on the underside of the carriage and threaded onto a leadscrew 44 rotatably supported in bearings 45 on the sub-carriage 29.Rapid advance of the wheel is effected by the rapid traverse motor 37rotating the nut along the screw at the same time the screw itself isbeing rotated by a feed motor 46 supported on the sub-carriage andgeared t0 one end of the screw. When the grinding wheel is apredetermined distance from the roll, the rapid traverse motor isstopped automatically while the feed motor continues to rotate the leadscrew to advance the wheel at a slower rate and into contact with theroll. The rapid traverse motor 37 is driven reversely to return thewheel rapidly to the retracted position upon completion of grinding ofthe roll.

In accordance with the present invention, a roll feeler 50 (FIGS. 2 and3) for sensing the diameter of the roll 20 coacts with a wheel feeler 51for sensing the prevailing diameter of the grinding wheel 25 to reduceautomatically the rate of advance of the wheel toward the roll when theperiphery of the wheel is a fixed distance short of the roll regardlessof the wheel and roll diameters. The roll feeler projects ahead of theperiphery of the wheel during rapid advance of the wheel, engages theroll ahead of the wheel to detect the diameter of the roll, andthereafter shifts rearwardly relative to the wheel and acts through afloating differential lever 53 (FIG. 3) to project the wheel feelerforwardly into feeling engagement with the periphery of the wheel. Thelatter feeler senses and correlates the diameter of the wheel with thediameter of the roll and de-activates the rapid traverse motor 37 justprior to the wheel contacting the roll.

In the present instance, the floating differential lever 53 is a toothedpinion which is journaled by a roller bearing 54 (FIG. 5) for rotationabout the axis of a horizontally disposed pin -55 fastened intermediatethe ends of an arm 56. The latter lies alongside the pinion and ismounted for back and forth reciproeation along one side of the carriage26 by a tubular guide 57 (FIG. 3) which is attached to the carriage andwhich slidably receives a cylindrical stem 59* rigid with the forwardend of the arm but offset laterally therefrom so as to lie in the planeof the pinion 53. Formed on the rear end of the arm 56 is a tongue 60(FIGS. 3 and 6) projecting laterally from the arm and behind theperiphery of the pinion 53 so that, in response to energization of areversible power actuator, herein an electrically operated solenoid 61fastened to the carriage 26, the armature 63 of the solenoid abutsagainst the tongue to shift the pinion bodily and forwardly through alimited range from a retracted position (FIG. 7) to an advanced position(FIGS. 3 and 8).

During the initial movement of the pinion to the advancedr position, apiston 64 (FIG. 6) formed with an arcuate face 65 concentric with theperiphery of the pinion engages and prevents rotation of the latter. Thepiston is telescoped slidably over the armature 63 and into a bore 66 inthe casing 67 of the solenoid and is urged against the pinion by a coilspring 69 housed within the bore. Near the end of the forward stroke ofthe solenoid, a shoulder 70 extending around the open end of the borestops further forward movement of the piston with the pinion so that thepinion is left free to rotate when disposed in the advanced position.De-energization of the solenoid results in the return of the pinion tothe retracted position through the action of a spring 71 (FIG. 3)telescoped over the stem 59 and into a bore 73 formed in the guide 57.

Guided for back and forth reciprocation above the pinion 53 in responseto bodily shifting of the axis 55 thereof is the roll feeler 50` whichherein is an elongated bar extending alongside the grinding wheel 25 andformed at its outer or free end with a depending finger 74 (FIG. 2)engageable with the work roll 20. Near its free end, the feeler isguided by a roller 75 (FIG. 2) journaled on the carriage while, at itsrear end, the feeler slides beneath a cap 76 (FIG. 5) and along one sideof a post 77 upstanding from the carriage, the cap 76 being fastened tothe upper end of the post by a screw 79. The motion of the pinion istransmitted to the roll feeler 50 by a rack 80 (FIGS. 3 and 5) which isformed on its lower side with teeth 81 meshing with the teeth of thepinion. The rack slides parallel to the feeler 50 along the oppositeside of the post 77 and is fastened at opposite ends to the feeler byscrews 83 (FIG. 3). A roller 84 (FIG. 5) is mounted for rotation on thepost and underlies the rack 80 to guide the latter.

As the pinion 53 is shifted from its retracted position (FIG. 7) to itsadvanced position (FIG. 8), the rack 80 moves bodily with the pinion andprojects the roll feeler 50 outwardly from a retracted position in whichthe linger 74 is disposed behind the periphery of the wheel 25 to anadvanced position in which the finger is disposed approximately l@ of aninch ahead of the wheel periphery. Starting with the roll feeler in itsadvanced position, the wheel is advanced rapidly toward the roll andthus the feeler engages and stops against the roll while the wheel isstill a short distance away from the roll (see FIG. 9). With continuedadvance of the wheel, the feeler, in effect, shifts rearwardly relativeto the carriage 26 and rotates the pinion about the axis of the pin 55.

Both the floating and the rotational movements of the pinion 53 aretransmitted to the wheel feeler 51 (FIG. 3) which herein comprises asupporting part or member 85 slidably mounted on the carriage 26 and afeeling part l86 slidably mounted on the supporting part. Generallystated, the two parts are shifted in unison from a retracted position(FIG. 7) to an advanced position (FIG. 8) when the solenoid 61 isenergized to shift the axis of the pinion forwardly. Thereafter and asthe roll feeler 50 engages the roll 20 and rotates the pinion, the twoparts 85, 86 continue to move as a unit from the advanced position andtoward the periphery of the wheel until the feeling part 86 moves intofeeling engagement with the wheel as shown in FIG. 9. Such feelingengagement may be achieved mechanically, as by means of a roller on thefree end of the feeling part engaging the wheel, or hydrostatically asillustrated herein and as later to be described. Upon moving intofeeling engagement with and detecting the prevailing diameter of thewheel, the feeling part stops while continued rotation of the pinionshifts the supporting part relative to the feeling part (see FIG. 10).Such relative shifting between the two parts is utilized to operate acontrol switch 87 (FIGS. 4, 7 and 10) which de-activates the rapidtraverse motor 37 to slow the advance of the wheel toward the roll.

More specifically, the supporting part 85 is a rack in the form of anelongated sleeve (see FIG. 3) which is disposed below the axis of thepinion 53 and which is formed along its upper side with a row of teeth89 meshing with the teeth of the pinion. Slidably mounting the sleeve 85for back and forth reciprocation in a path parallel to the carriage inresponse to shifting and rotation of the pinion is a guideway 90 (FIG.5) attached to the side of the carriage and formed along its lower sidewith a horizontal flange or track 91 along which rides a roller 93journaled on the sleeve. As shown most clearly in FIG. 5, the upper sideof the guideway includes a pair of laterally spaced rails 94 extendingalong and guiding opposite sides of the rack teeth 89.

Preferably, the feeling part 86 is an elongated tube which is telescopedinto the sleeve 85. A coil spring 95 (FIGS. 3 and 4) surrounding therear end portion of the tube 86 and compressed between opposingshoulders 96 and 97 (FIG. 4) on the sleeve and the tube normally couplesthe two for movement axially in unison but yields to allow sliding ofthe sleeve on the tube when the latter is stopped as a result of movinginto feeling engagement with the wheel 25. The spring 95 urges the tubeforwardly in the sleeve and to a position limited by engagement of therear end of the sleeve with a collar 99 (FIGS. 3 and 4) fastened to therear end of the tube. The collar carries a switch operator 100- whichnormally is urged against the control switch 87 to hold the latter open,the control switch being attached to one side of the sleeve S5 near therear end thereof.

The forward end of the tube 86 projects beyond the forward end of thesleeve 85 and is slidably bushed in an arcuate hood 101 (FIG. 3) whichencircles and covers a substantial arc of the grinding wheel 25.Herein,'liquid coolant under high pressure, for example 100 p.s.i., isadmitted into ahe rear end of the tube through a conduit 103communicating with a coolant source (not shown) and is conducted to anozzle 104 which is fastened to the forward end of the tube by screws105. Formed in the nozzle and communicating with the tube is a recess orhydrostatic pad 106 which directs a high velocity jet of the coolanttoward the periphery of the wheel. As the rotating pinion moves thesleeve and the tube in unison from their advanced positions (FIG. 8) andprogressively closer toward the wheel, the jet of coolant impingesagainst the wheel periphery and creates an increasingly high backpressure between the pad 106 and the wheel. When the pad is in feelingengagement with and about .010 of an inch from the wheel (FIG. 9), theforce of the developed back pressure overcomes the force of the spring95 coupling the tube 86 and the sleeve 85 and, as a result, the pad 106stops short of the wheel while the spring 95 yields to permit relativesliding of the sleeve along the tube (see FIG. 10i) upon continuedrotation of the pinion. Such relative sliding moves the control switch87 away from the switch operator 100 and thus de-activates the rapidtraverse motor 37.

SUMMARY OF OPERATION Assume at the start of a cycle that the Wheel 25 isretracted away from the roll 20 and that the pinion 53 and the twofeelers 50, 51 are disposed in their retracted positions as shown inFIG. 7. Upon manual closure of start-stop switch contacts 107 and 108(FIG. 13), the rapid traverse and feed motors 37, 46 are started toadvance the wheel rapidly toward the roll. At the same time, thesolenoid 61 is energized through switch contacts 107 to shift the pinion53 and the two feelers all as a unit to their advanced positions (FIG.8). The roll feeler 50, projecting ahead of the wheel during advance ofthe carriage 26, engages and stops against the roll (FIG. 9) while thewheel is still about 1A of an inch short of the roll and, with continuedadvance of the carriage, slides rearwardly relative to the carriage andacts through the rack 80 to rotate the pinion 53. Through the rack teeth89, the rotating pinion 53 shifts the sleeve 85 and tube 86 toward thewheel, the two initially moving in unison due to the coupling spring 95(see FIG. 9). Approach of the pad 106 into feeling engagement with thewheel causes the back pressure between the two to increase sufficientlyhigh to overcome the force of the spring 95 and to stop the tube 85 sothat, with continued movement of the carriage 26 and rotation of thepinion produced by continued advance of the carriage with the rollfeeler 50 contacting the roll, the sleeve 85 slides forwardly on thetube l86 by yielding of the spring 95 and moves the control switch 87away from the switch operator 100 to close the switch 87, energize arelay 109, and de-activate the rapid traverse motor 37 through a switch110 which is opened by energization of the relay.

Opening of the switch 110 also de-energizes the solenoid 61 which allowsthe spring 71 to retract the roll feeler 50 behind the periphery of theWheel 25 (FIG. 11) and out of contact with the roll 20 and to retractthe pad 106 away from the wheel. During retraction of the pad, thespring 95 relaxes and slides the sleeve 85 rearwardly on the tube 86 tomove the control switch 87 back into contact with the switch operator100 preparatory to the next advance of the wheel. The control switch 87reopens but the relay 109 remains energized to hold switch 110 openthrough a holding circuit set up by start-stop switch contacts 108 andrelay-actuated switch contacts 111. Accordingly, the solenoid 61 and therapid traverse motor 37 are held de-energized during grinding of theroll. The relay 109 is de-energized at the completion of a grindingcycle when start-stop contacts 108 are opened.

The advantages of the foregoing arrangement are apparent. The wheelfeeler 51 is not moved from its advanced position and toward feelingengagement with the wheel 25 until the roll feeler 50 engages anddetects the diameter and location of the roll. Even when moved by theroll feeler, the wheel feeler does not actuate the control switch 87until the pad 106 actually moves into feeling engagement with anddetects the prevailing diameter of the wheel. Thus, regardless of thediameters of the wheel and the roll, the reduction in the advance ratealways will occur when the wheel periphery is a fixed distance short ofthe roll. During service use, the wheel wears down and decreases indiameter so that, when the roll feeler is shifted to its extendedposition between successive advances of the wheel toward the roll, theextent of projection of the finger 74 ahead of the wheel periphery, ineffect, will be just slightly greater than on the last previous advance.Moreover, the roll feeler will shift the sleeve 8S and the tube 86 inunison relative to the carriage through a greater distance before thepad moves into feeling engagement with the worn wheel and before theback pressure stops the tube. As a result, the position of the tube andthe sleeve shifts forwardly in small increments between successiveadvances to delay the changeover in the advance rate in accordance withthe diameter of the wearing wheel. This is illustnated schematically inFIG. 12 which shows a wheel 25' worn down to a diameter considerablysmaller than its original diameter. As is apparent, the sleeve 85 andthe tube 86 have moved to positions considerably farther forward on thecarriage than was the case with the wheel 25. Thus, each time the twofeelers 50, 51 are returned to their retracted positions by the solenoidbetween successive advances of the carriage, they assume positions whichare spaced short increments rearwardly and forwardly, respectively, oftheir corresponding positions before the advance of the carriage. Thelength of the increments is equal to the amount of wheel wear duringgrinding, that is, equal to the decrease in the radius of the wheel.

The incremental shifting of the sleeve along the carriage 26 as thewheel 25 wears is used to advantage to increase the rotational speed ofthe wheel automatically in response to wheel wear thereby to maintainconstant the peripheral speed of the wheel. For this purpose, a cam 113(FIG. 3) is carried by the lower side of the sleeve 85 and rides along apointed follower 114 which is carried at the upper end of a rack 115guided for up and down sliding in a bracket 116 fastened to the carriage26. As the cam and the sleeve shift forwardly in small increments, thefollower and the rack are released to the action of a spring 117stretched between the bracket and the lower end of the rack and, as aresult, the rack slides upwardly and turns a pinion 119 which is fast onthe operating shaft of a potentiometer 120 connected in the controlcircuit of ahe grinding wheel motor 35. Turning of the pinion 119adjusts the potentiometer in accordance with the amount of wheel wear,and the potentiometer increases the speed of the wheel motor 35 tomaintain the peripheral speed of the wheel at a constant value in spiteof such wear.

I claim as my invention:

1. In a grinding machine, the combination of, a support for mounting ahorizontally disposed work roll to turn about its longitudinal axis,carriage mounted on said support to move toward and away from the rollalong a path extending generally transversely of said roll axis, a powerdriven grinding wheel mounted for rotation on said carriage andengageable with the roll along a surface thereof, a power operatorselectively operable to advance said carriage along said path toward theroll at rapid and slow rates, a differential lever mounted on saidcarriage for turning about an axis and also for bodily oating toward andaway from the roll, a reversible power actuator energizable selectivelyto shift said level axis relative to said carriage and toward and awayfrom said roll through a limited range between advanced and retractedpositions, an elongated roll feeler coupled to said lever on one side ofthe axis thereof and mounted on said carriage for endwise movement inresponse to shifting of said lever axis, said feeler having a free enddisposed respectively ahead of and behind the periphery of said wheel insaid advanced and retracted positions of said lever axis, an elongatedwheel feeler coupled to said lever on the opposite side of said leveraxis and comprising a supporting part slidable back and forth on saidcarriage parallel to said path, said wheel feeler further comprising afeeling part slidable on said supporting part parallel to said path andhaving a free end movable forwardly into feeling engagement with theperiphery of said wheel on the side thereof opposite said roll, meansyieldably biasing said feeling part relative to said supporting part andtoward said wheel periphery, said roll feeler, when held ahead of thewheel by said actuator and with said wheel feeler retracted out offeeling engagement with said wheel, acting, during the rapid advance ofsaid carriage toward the roll and after engaging the roll, to shiftrearwardly relative to said carriage, turn said lever about said leveraxis and thereby shift said supporting and feeling parts in unisontoward the wheel periphery and then, after feeling engagement of saidfeeling part with said wheel, to continue to shift said supporting partrelative to said feeling part by yielding ofsaid biasing means, andmechanism operable in response to such relative shifting of saidsupporting and feeling parts to control said operator and change theadvance of said carriage from said rapid rate to said slow rate.

2. A grinding machine as defined in claim 1 in which said differentiallever comprises a pinion rotatable about said lever axis and meshingwith rack teeth carried by said roll and wheel feelers.

3. A grinding machine as defined in claim 1 in which said actuator isenergized and de-energized to shift said lever to said advanced andretracted positions, respectively.

4. A grinding machine comprising, in combination, a support rotatablymounting a roll to be ground, a carriage mounted for movement back andforth along a path extending generally transversely of said roll, anabrasive wheel for grinding said roll mounted on said carriage and powerrotated about an axis extending generally transversely of said path, apower operator selectively controllable to advance said carriagealongsaid path and toward said roll at rapid and slow rates, a feelerprojecting along said path ahead of the periphery of said wheel forengagement with said roll and mounted on said carriage for movementrelative thereto along said path so as to be retracted progressively inthe advance of said carriage following engagement of the feeler withsaid roll, a wheel feeling part, a member mounted on said carriage formovement relative thereto and supporting said feeling part for feelingengagement with the wheel periphery, means biasing said feeling partrelative to said member toward said wheel and to a predetermined normalposition relative to the member, mechanism coupling said roll feeler andsaid member and operable during retraction of the roll feeler in therapid advance of the carriage after the roll feeler engages said roll toadvance said member and feeling vpart toward said wheel and afterfeeling engagement therewith to permit continued movement of the memberin the continued retraction of the roll feeler, and means responsive tosaid continued movement of said member to control said power operatorand change the advance of said carriage from said rapid rate to saidslow rate.

5. A grinding machine as defined in claim 4 in which said couplingmechanism includes a device mounted on said carriage for bodily movementback and forth along said path and coupled to said roll feeler and saidmember for movement of the two back and forth in the same direction andin unison.

6. A grinding machine as defined in claim 5 including a power actuatorselectively operable to shift said device back and forth along said paththrough a limited range sufcient to retract said roll feeler behind saidwheel periphery after termination of the advance of said carriage atsaid slow rate.

7. A grinding machine as defined in claim 4 further including a motor onsaid carriage for rotating said abrasive wheel, a cam carried by andmovable with said member, and means on said carriage and engageable withsaid cam and responsive to movement thereof to increse the speed of saidmotor and the rotational speed of said abrasive wheel as the latterwears down and decreases in diameter.

References Cited yUNITED STATES PATENTS 2,802,312k 8/1957 Gosney et al.51-165 l2,961,808 1l/l960 Dunigan 5l--l65 HAROLD D. WHITEHEAD, PrimaryExaminer p Us. C1. X.R. 51 134.5

